It was approaching midnight on Oct. 16, 1915, when Methodist preacher William Joseph Simmons and at least 15 other men climbed Stone Mountain in Georgia. They built an altar, set fire to a cross, took an oath of allegiance to the “Invisible Empire” and announced the revival of the Ku Klux Klan.

Beneath a makeshift altar glowing in the flickering flames of the burning cross, they laid a U.S. flag, a sword and a Holy Bible.

“The angels that have anxiously watched the reformation from its beginnings,” said Simmons, who declared himself Imperial Wizard, “must have hovered about Stone Mountain and shouted hosannas to the highest heavens.”

Last Wednesday — on the 50th anniversary of the assassination of the Rev. Martin Luther King Jr. — progressive faith groups held a march in Washington to combat racism and atone for the history of that prejudice.

“Without confession of the sin of white racism, white supremacy, white privilege,” the Rev. Jim Wallis, founder of the progressive Christian group Sojourners, said, “people who call themselves white Christians will never be free.”

Wallis didn’t refer directly to the Klan, which had terrorized black people during Reconstruction before being dismantled by President Ulysses S. Grant. It was “born again” that night in 1915 on Stone Mountain, and Christianity was used to justify a second wave of terror.

A mass Klan initiation ceremony at Stone Mountain on July 23, 1948. (AP)

Restricting membership to white Christians, the Klan wore white robes to symbolize “purity,” burned crosses to signify “the Light of Christ” and picked selective scriptures from the Bible to preach white supremacy. The Invisible Empire’s comeback was aided by Hollywood’s first blockbuster, D.W. Griffith’s “The Birth of a Nation,” which glamorized the Klan.

By the early 1920s, the Klan boasted 5 million members across the country and had infiltrated thousands of churches with its hateful doctrines.

Many ministers in Protestant denominations would openly declare their membership in the Klan. And creepy photos would capture Klan members in white hoods standing in churches and sitting in choir pews.

In a 1922 article, the New York Times reported “The Ku Klux Klan in the South and West is largely dominated by ‘lame duck’ preachers who could not make it good in the ministry.”

“So far as I have been able to see,” the Rev. John Roach Straton preached to a New York congregation, “the Klan in the South and West seems to be largely under the domination and leadership of a lot of lame duck preachers. They play out in the ministry, and then instead of selling insurance or peddling churns, as they did in former times, they devote their time and talents to ‘saving the country’ by organizing men into secret, disguised societies and dressing them up in nightgowns and dunce caps.”

Simmons believed Christianity supported white supremacy, Kelly J. Baker, author of the book, “The Gospel According to the Klan,” said in an interview. “He and other Klan leaders would look to Christianity to find support for racism. Even liberal Protestant churches supported white supremacy. That seemed the natural order of things. Just as people used biblical texts to support slavery.”

In 1921, Simmons testified to Congress that he was a minister in not one church but two.

“As a brief introduction, please, I am a churchman and proud of it. I hold the distinction, which I suppose few men hold, and that is I am a member of two churches — the Congregational Church and a full-fledged associate member of the Missionary Baptist Church, given me as an honor,” Simmons told the House Rules Committee, which was investigating the Klan and “the terrible things being done to innocent people” in the South.

In Klan propaganda and its 1916 rule book, Simmons said that only “good Christian white people” who believe in racial purity and Protestant morality would save the country from destruction.

Meeting of the KKK, probably in Portland, Ore., in the 1920s. (Oregon Historical Society)

“Hate in God’s Name,” a 2017 report by the Southern Poverty Law Center, says that white supremacist groups often invoke scripture from the Old and New Testament.

“This is particularly applicable to Ku Klux Klan (KKK) members,” the report says, “Christian Identity adherents and some neo-Nazis. White supremacists believe mainstream religions, including Christian denominations and their institutions, have fallen astray from God and are under the control and influence of Satan. As a result, white supremacists interpret scriptures and spiritual parables through the lens of racial discrimination and hate. In this way, they can justify their beliefs (which are vile and deplorable) as good, moral and responsible.”

Klan members believe “the Bible is the family history of the white race,” according to the report. “They believe that white Christians are morally and spiritually superior to other races.”

The Klan symbol, displaying a white cross with a red tear drop, “symbolizes the atonement and sacrifice of Jesus Christ, as well as others who have shed their blood for the white race,” says the report, noting that “some KKK leaders are actually ordained ministers and some have even organized churches which enjoy tax-exempt status.”

In his 1921 testimony to Congress, Simmons said he relaunched the Klan after watching the film “The Birth of a Nation.” The 1915 racist blockbuster promoted the Klan as the great defender of “white womanhood.” President Woodrow Wilson showed the film at the White House.

Klansmen are the heroes of D.W. Griffith’s racist blockbuster, “The Birth of a Nation.” (AP)

With the help of a public relations team, headed by Edward Clarke and Elizabeth Tyler, the Klan’s rosters exploded.

“The popularity came from the combination of religion and nationalism it promoted, both of which appealed to white Protestant Americans who feared that immigration and changing social mores would overthrow their social dominance,” wrote Baker.

Simmons, born in 1880 on a farm in Harpersville, Ala., was an itinerant Methodist minister. He established himself as “Imperial Wizard” and created a pamphlet, which he called “The ‘Fiery’ Summons.” The pamphlet featured a drawing of a masked horse and rider in a robe carrying a burning cross with a headline that read “Yesterday Today and Forever.” According to the Georgia Encyclopedia, the Methodist Episcopal Church eventually suspended Simmons for “inefficiency.”

In his congressional testimony, he described the Klan as simply a “fraternal, patriotic, secret order for the purpose of memorializing the great heroes of our national history, inculcating and teaching practical fraternity among men, to teach and encourage a fervent, practical patriotism toward our country. …”

Simmons recounted how he came up with the idea of relaunching the organization 15 years before he climbed Stone Mountain. He was inspired by a “religious vision” of men in white robes riding horses across the horizon, he said.

“The charge has been made that the Klan takes the law into its own hands; that it terrorizes private citizens in many communities by lawless acts against person and property,” Simmons told the House committee.

“These charges,” Simmons said, “are untrue.”

A year later in 1922, amid political infighting within the organization, Hiram Wesley Evans, a dentist, replaced Simmons as the group’s Imperial Wizard. Simmons died in 1945 in Atlanta.

An Associated Press obituary that appeared in the New York Times described Simmons this way: “If any one was responsible for the founding of the second Knights of the Ku Klux Klan it was Mr. Simmons, preacher, traveling salesman and promoter of fraternal organizations. … From his ‘imperial palace’ on Peachtree Road in Atlanta, Imperial Wizard Simmons ruled the ‘Invisible Empire’ of his bed-sheeted followers.”

The obituary offered a final condemnation of the Simmons’s legacy: “The organization, deeply rooted in native ignorance, flourished in rural areas. Its members liked to call themselves kleagles, goblins and other names of darkling potency, to meet in solemn ‘konklaves,’ burn a fiery cross upon a distant hill and, perchance, frighten a Negro child outnumbered 100 to 1. Sometimes, too, Klans-‘men’ lynched, tortured and beat the helpless.”

Correction: An earlier version of this story stated that President Wilson praised “Birth of a Nation and called it “all so terribly true.” Some historians do not believe he ever said this, and the reference to the quote has been removed.